1,3,5-Cycloheptatrienes electrocyclic ring closure

Problem 4.5. Cycloheptatriene undergoes rapid electrocyclic ring closure under thermal conditions. Determine the structure and stereochemistry of the product. 

A more detailed investigation of the photochemistry of 5-substituted 1,2-benzo-cycloheptatrienes has shown that [2,3]benzonorcaradienes can be obtained by [1,7]H shift. However, electrocyclic ring-closure across C-3—C-6 competes favourably, and (44) is unusual in that only the norcaradiene product is obtained... 

Norcaradiene formation from a cycloheptatriene corresponds to a 1,3-ring-closure. On the basis of this reaction, aminocyclopropane 317 was obtained as a solid in 94% yield from piperidine and the tropylium ion 315 (equation 74). A rapid equilibrium between 316 and 317 was postulated in solution. Electrocyclic 1,3-bond connections also were involved in the fluctual behaviour of 9-azabarbaralanes " , in the formation of homoazepines (from nitrenes and cycloheptatriene" " ) and in a 6-azabenz[10]annulene system . ... 

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